The cake Timmy throws at Jimmy is a strawberry cake, but the one that lands on Jimmy is chocolate. As the scene ends, the cake Timmy threw is back on the table, but the cookies and donuts are gone.
The color on Big Gay Al's living room floor changes from white to brown. When that happens, a tall cup appears on the table, disappears, and then reappears.
When Cartman yells "Cripple Fight" in church we can see Mr. McCormick running to see it too, but after some shots we see him sitting in the pub with other children's parents.
During the last scene when the children are at scouts, Timmy is seen in the top left corner of the table where the scout leaders sit. He is then seen steering his wheelchair in from the right side of the screen in the next shot as if he was sitting on the right side of the scout leaders.
When Eric Cartman runs around town yelling "CRIPPLE FIGHT!" he runs into a church, and the Broflovski's (excluding Kyle and Ike) can be seen on the far left side of the church, despite the fact that they are Jewish, not Catholic.